No, in my experience 90% is about right. And here's the problem with
a bad jug - the best maintained planes get them. You can't tell
without doing a compression check - the power loss is not noticeable.

In my case, the Warrior had a thorough pre-buy, by a reputable shop, the
compressions were great -- but the jug nevertheless failed a few months
later, because the engine was actually missing a critical internal part. No
pre-buy on earth would have detected that missing rotator cap -- unless they
were tearing the engine down.

Buying an old plane is always a roll of the dice, but -- had I known then
what I know now -- I would have more thoroughly researched the *seller*, not
so much the aircraft.

The seller was an FBO manager, from Marshfield, WI. I found out later that
he was apparently selling off his aircraft to pay his way out of bankruptcy.
Had I known that at the time, I would have walked away from the table, since
a guy going bankrupt is NOT going to be able to maintain an aircraft
properly. That missing rotator cap -- left out because he probably had the
wrong length push-rod in stock -- could have killed me.

Ah, well. It's now the finest Warrior, anywhere -- so all's well that ends
well.

(Besides, I'd have just spent all that money in the bars probably anyway...)

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"